Switchgear configurations have current limits based on the heat rise over ambient room temperature. It is generally desired to limit the maximum temperature of the hottest spot on the switchgear main bus to 105° C. (a rise of 65° C. over an assumed ambient temperature of 40° C.), as directed by the standard IEEE 37.20.2. Typical medium and high-voltage metal-clad switchgear arrangements have maximum continuous current ratings of about 3000 A, due to heat generation. It is desirable to increase this current rating to 4000 A and above.
With reference to FIG. 1, a conventional heat pipe based cooling system, generally indicated at 10, offers an additional path for heat dissipation to the ambient environment outside a switchgear enclosure 12. Such a system is disclosed in co-pending U.S. application Ser. No. 13/444,888, filed on Apr. 12, 2012. Heat can be transported from a heat source very effectively by making use of a thermally driven evaporation and condensation process, and subsequently dissipated to a heat sink. Heat pipes are vacuum tight systems, partially filled with a working fluid. A dedicated evaporator section (heat input from the switchgear), generally indicated at 14, can be connected to a condenser 16 (heat output to the environment) by means of flexible and very compact heat pipe or tubing structure 18. Such a system can be employed as an integral part of the switchgear enclosure system without breaching the requirements for self-contained compartments.
The switchgear equipment could be cooled by one common heat pipe network, with one condenser serving as heat sink, or with several heat pipes, which are operated in parallel and with independent, rectangular-box type condensers 16. The condenser 16 is preferably located at the backside or on top of the switchgear housing 12.
The condenser outlays account for about 50% of the total cost of the system. Also, a conventional condenser 176 is built from one large aluminum rectangular body with six independent chambers for each of the heat pipes, which leads to a heavy construction that is cumbersome for installation.
Thus, there is a need to provide condenser structure that reduces manufacturing cost and that is modular and easy to install in a limited space.